The invention relates to a support structure in framework construction, and in particular to a support structure of an axle carrier of a motor vehicle, and to a corresponding method for producing same.
A support structure in framework construction includes a multiplicity of rods, wherein the two ends of each rod bear against respective truss joints or nodes on other rods or on corresponding ends of the other rods and are fastened to the other rods by use of a suitable connecting element.
Where metal is used as the material for the rods, the fastening can be realized, for instance, by welding. Furthermore, the rods can by fastened one to another by bolted joints, rivets or by the use of a connecting element having curved portions which at least partially enclose the rods to be connected and which are fastened to the rods by means of an adhesive. Where an adhesive is used to connect the rods to the curved portions of the connecting element, large areas of the connecting element must however be provided as adhesive surfaces in order to achieve sufficient stability of the support structure, which leads to an increase in weight of the support structure.
In order to reduce the weight and thus lower the fuel consumption of a motor vehicle, in the automotive industry components in lightweight construction are increasingly being used. For instance, as the material for the rods of an axle carrier, fiber-reinforced plastics can be used. Particularly where carbon fibers are used as the fiber component of the fiber-reinforced plastic in conjunction with aluminum, a corrosion of the aluminum material can occur, however, due to the very high electrical potential between these two materials. Furthermore, where bolted joints are used to connect the ends of the rods at the nodes, complex assembly operations are necessary, whereby the production time required to produce the axial carrier, and thus the production costs, are increased.
An object of the invention is to provide a support structure in framework construction and a method for producing same, with which the product costs can be lowered, at the same time as the weight of the support structure is reduced.
These objects are achieved by a support structure in framework construction and a method for producing a support structure in framework construction according to embodiments of the invention.
A support structure in framework construction according to the invention includes a first and a second rod of an axle carrier of a motor vehicle, a positioning element, and a first and a second fiber winding, wherein the positioning element defines an orientation of the first rod relative to an orientation of the second rod, and a first supporting portion of the positioning element is drawn by the first fiber winding in the direction of a supporting portion of the first rod, and a second supporting portion of the positioning element is drawn by the second fiber winding in the direction of a supporting portion of the second rod, in order to secure the first and the second rod in the defined relative orientation to each other by way of frictional engagement.
Through the use of fiber windings to connect the rods, where rods made of a non-metallic material are used, the danger of corrosion of elements of the support structure can be precluded. Furthermore, the production time and thus the production costs of the support structure can be lowered, since complex assembly operations, as in the use of rivets for fastening purposes, are eliminated. In addition, the weight can be reduced in comparison to previous known adhesive joints, since, due to the provision of the fiber windings, no extensive adhesive surfaces on the rods are necessary. Because of the unnecessary extensive adhesive surfaces on the rods, these can be produced in a cost-effective manner, for instance, by way of a pultrusion process.
According to one embodiment, the first and the second supporting portion of the positioning elements can have a respective guide device, by which the first and the second fiber winding are respectively guided. The guide devices are here preferably designed such that the fiber windings run on geodetic lines. As a result, the stability of the support structure can be increased, since the fiber windings cannot slip off, which would lead to instability of the connections.
Preferably, the first supporting portion of the positioning element is fastened to the supporting portion of the first rod, and the second supporting portion of the positioning element is fastened to the supporting portion of the second rod, additionally by way of an integrally bonded connection.
Already prior to the fitting of the fiber windings, the integrally bonded connection ensures that the relative orientation of the rods is defined, whereby the fitting of the fiber windings is facilitated. Furthermore, the stability of the support structure is further increased by the provision of the integrally bonded connections.
The integrally bonded connections can be realized by respective adhesives provided between the first supporting portion of the positioning element and the supporting portion of the first rod, and the second supporting portion of the positioning element and the supporting portion of the second rod.
According to one embodiment, a distance between an end portion of the positioning element, which end portion adjoins an exposed portion of the first rod, decreases steadily or incrementally in the direction of another end portion of the positioning element down to a substantially constant value. As a result of this design, notch effects can be improved and peak stresses dampened. Furthermore, adjoining the end portion of the positioning element, a protruding bead, consisting of adhesive, can be formed in order to further dampen the peak stresses.
Preferably, the positioning element is configured as a half-shell, whereof the surface facing the supporting portion of the first rod rests by positive engagement on the supporting portion of the first rod. As a result of this positive engagement, a further increase in the stability of the support structure is achieved.
In another embodiment, the positioning element can be configured as a tongue, wherein the first supporting portion and the second supporting portion of the positioning element are connected by a curved portion. The curvature of the curved portion here defines an angle which the first and the second rod form with each other.
The fiber windings can include at least one fiber, selected from a carbon fiber, a glass fiber, an aramid fiber and a natural fiber.
The at least one fiber can here be embedded in a matrix material, selected from a thermoplastic matrix material and a thermosetting matrix material.
In addition, the first rod and/or the second rod can include a fiber-reinforced plastic or a metal, and the positioning element can be formed from a plastic, a fiber-reinforced plastic or from a metal.
Preferably, the first and the second rod and the positioning element are formed from a fiber-reinforced plastic, wherein the fiber windings are respectively constituted by a fiber winding formed from a synthetic fiber.
As a result of this material-related design of the corresponding elements of the support structure according to the invention, no corrosion occurs and, in addition, the first and the second rod, the positioning element and the fiber windings can be designed such that they have the same or similar thermal coefficients of expansion.
A method for producing a support structure in framework construction arranges a first supporting portion of a positioning element on a supporting portion of a first rod of an axle carrier of a motor vehicle, arranges a second supporting portion of the positioning element on a supporting portion of a second rod of an axle carrier of a motor vehicle, connects the first supporting portion of the positioning element to the supporting portion of the first rod by a fiber winding, which draws the first supporting portion of the positioning element in the direction of the supporting portion of the first rod, and connects the second supporting portion of the positioning element to the supporting portion of the second rod by a further fiber winding, which draws the second supporting portion of the positioning element in the direction of the supporting portion of the second rod, in order to secure the first and the second rod in a defined relative alignment to each other via frictional engagement.
The first and the second supporting portion of the positioning element can have a respective guide device, wherein portions of the first and of the second fiber winding are respectively inserted into the corresponding guide device.
Furthermore, the first supporting portion of the positioning element can be fastened to the supporting portion of the first rod, and the second supporting portion of the positioning element can be fastened to the supporting portion of the second rod, by way of an integrally bonded connection.
For the creation of the integrally bonded connections, respective adhesives can be provided between the first supporting portion of the positioning element and the supporting portion of the first rod, and the second supporting portion of the positioning element and the supporting portion of the second rod.
Preferably, a distance between an end portion of the positioning element, which end portion adjoins an exposed portion of the first rod, decreases steadily or incrementally in the direction of another end portion of the positioning element down to a substantially constant value.
Furthermore, adjoining the end portion of the positioning element, a protruding bead, consisting of adhesive, can be formed.
Preferably, the positioning element is configured as a half-shell, whereof the surface facing the supporting portion of the first rod is placed by positive engagement on the supporting portion of the first rod.
According to another embodiment, the positioning element can be configured as a tongue, wherein the first supporting portion and the second supporting portion of the positioning element are connected by a curved or arcuate portion.
The fiber windings can comprise at least one fiber, selected from a carbon fiber, a glass fiber, an aramid fiber and a natural fiber.
Furthermore, the at least one fiber can be embedded in a matrix material, selected from a thermoplastic matrix material and a thermosetting matrix material.
The first rod and/or the second rod can include a fiber-reinforced plastic or a metal, or can be formed completely of a fiber-reinforced plastic or a metal, whilst the positioning element can be formed from a plastic, a fiber-reinforced plastic or from a metal.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.